Water-flow power generating apparatuses that generate electricity by utilizing the energy of a water flow of oceans or rivers (an ocean current, a tidal current, a river current), are attracting attention. Such a water-flow power generating apparatus is installed in the water and includes a rotor that includes blades to receive a water flow, a power generating unit that converts a rotation force of a rotor into electrical energy, and a nacelle that covers the power generating unit from outside. As such a water-flow power generating apparatus, an apparatus described in, for example, the following Patent Literature 1 has been known. The apparatus described in Patent Literature 1 includes, as a bearing unit for supporting a rotor in a rotatable manner, a thrust bearing that supports the axial direction load of the rotor and a radial bearing that supports the radial direction load of the rotor. Each of these thrust bearing and radial bearing is a water lubricated bearing that takes in external water and uses the external water as a lubricant.
Moreover, hitherto, there have been known technologies relating to a water-flow power generating apparatus that generates electricity by utilizing the energy of a water flow of oceans or rivers (an ocean current, a tidal current, a river current). For example, in Patent Literature 2, disclosed has been a power generating apparatus equipped with a power pod that includes a floating pressure vessel and a rotor assembly to which blades are connected and generates electricity when the blades are driven by a water flow. In this water-flow power generating apparatus, the rotor assembly is supported rotatably relative to the floating pressure vessel by a fluid bearing.